What Exactly Are IBUs?

West Coast IPAs are notorious for being bitter, bitter beers. While some choose to embrace the hops, others bring out the bitter, even though hops can also be bitter. Both are bitter. IPAs are usually pretty bitter, full of IBUs.

Bitterness has always been a thing in beer, and at some point in human history, there was a decision made to measure the bitterness of any given beer.

In America, we use the International Bittering Units scale (IBU) to pinpoint just how bitter a beer is. When speaking, we ask what the IBU of a beer is. This is basically just saying, “hey, how bitter is your beer?”

While many things about beer are easy and fun, IBUs are, in my opinion, neither. Part of the reason is that, as far as I can tell, some breweries swill measure their IBUs differently. I don’t know why.

Before getting into the math (yes, there’s math involved), let’s learn more about bitterness.

Let’s Learn More About Bitterness

IBUs work well with ABV – while ABV tells you how a beer will make you feel, IBUs give you a hint at how your beer will taste. That’s why they are the most traditional numbers to use when presenting beer (there are plenty of others, like density, but that’s a whole nother story).

IBUs are pretty simple, too: the lower the IBU, the less bitter the beer. Technically, the lowest IBU possible is 0, but when a beer is that low it may be more common to just ignore measuring them altogether (as we found out during a recent beer tasting).

To give you an idea of IBUs, here are some popular beers and their IBU:

Coors Light: 10

Corona Light: 13

Heineken: 23

Sierra Nevada Pale Ale: 37

Guinness: 40

Stone IPA: 71

Flying Monkeys Alpha Fornication: 2500

I’ve never had the Flying Monkeys beer, but if you want to send me money to buy and taste it that’s ok with me.

Right about now you probably have two things on your mind:

  1. I’m never sending you money, Thomas.
  2. Wait, Guinness has more IBU than Sierra Nevada? But Guinness isn’t bitter!

The second point is a good point. Why is that? Well, Guinness is bitter, but it’s also a stout which means it’s heavy on malt.

Sierra Nevada, on the other hand, is one of those breweries that likes to accentuate the bitterness of a brew. Even though it has a lower IBU, the beer presents the hops better by reducing malt.

How Are IBUs Measured?

IBUs are calculated by taking a measurement of boiling hops, taking the percentage of alpha acid and taking the total hop utilization boil time – then multiplying all of them and dividing them by 7.25 for every 5 gallons of beer.

Let me break this down for you.

Let’s say we use an ounce of some citra hops. Perfect and delicious. These hops have alpha acids; more specifically, let’s say they’re 12% alpha acid. We’re single hopping this to keep it easy, so let’s say 31% utilization.

To crunch the numbers, just do 1 x 12 x 31 = 372. Then we divide this by 7.25, so our total IBU would be 51.3.

Honestly, that makes sense to me since citra hops are used commonly in IPAs, and IPAs should be around 40-60 IBU (unless they’re bitter heavy).

If we were to have other hops and utilization, we would take their alpha acids, punch in the utilization and then add all the IBU totals together.

I know, it’s confusing to try and teach through writing. I don’t write math text books, I write about beer.

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